Rotary tool as well as carrier and cutting insert for such a rotary tool

ABSTRACT

The invention relates to a rotary tool as well as to a carrier and a cutting insert of such a rotary tool. The carrier comprises a seat, which comprises several lateral surfaces, between which the cutting insert can be inserted. The cutting insert comprises, for each of the lateral surfaces, a contact surface which abuts against the respective lateral surface in an inserted state. At least one coolant channel is formed, which comprises a first partial channel and a second partial channel, which adjoins the first partial channel, wherein the first partial channel proceeds within the carrier up to an outlet opening, wherein the second partial channel proceeds within the cutting insert from an inlet opening up to a coolant outlet, wherein the outlet opening and the inlet opening form an interface for transferring coolant from the carrier to the cutting insert. The outlet opening is arranged in one of the lateral surfaces and the inlet opening is arranged in one of the contact surfaces.

RELATED APPLICATION DATA

The present application claims priority pursuant to 35 U.S.C. § 119(a)to German Patent Application No. 102017214165.4 filed Aug. 14, 2017,which is incorporated herein by reference in its entirety.

FIELD

The invention relates to a rotary tool comprising a carrier and acutting insert as well as to a corresponding carrier and a correspondingcutting insert.

BACKGROUND

A rotary tool, in short tool, serves to machine a workpiece. Givenspecific materials or machining methods, an additional supply of coolantor lubricant is necessary or at least advantageous. Since the thermalload is generally highest at the machining site, i.e., at the contactpoint of the tool on the workpiece, it is moreover expedient to deliverthe coolant to this site. To this end, the tool often times comprises atleast one coolant channel, by means of which a lubricant can alsogenerally be delivered. The coolant channel extends thereby along thetool such that an outlet opening results at a suitable point. Forexample, in the case of a rotary tool, the outlet opening of the coolantchannel can be arranged on the end surface side or in flutes of therotary tool.

Particularly highly loaded rotary tools are moreover often timesdesigned to be modular. Such a modular rotary tool generally comprises acarrier, to which is attached a cutting insert, which engages with theworkpiece during operation. In this case, the carrier comprises a seat,into which the cutting insert is inserted. The coolant is generallyconveyed in the direction of the cutting insert via a coolant channelintroduced into the carrier, since the cutting insert is generallyloaded more than the carrier and requires appropriate cooling. It isbasically possible to guide the coolant channel exclusively through thecarrier to the front side of the tool. In doing so, the coolant howevercannot be conveyed arbitrarily close to the contact point. In DE 10 2014108 220 A1, for example, a transfer of the coolant from the carrier tothe cutting insert therefore takes place first in order to ultimatelydeliver the coolant via coolant outlets of the cutting insert on the endsurface side.

To this end, the coolant channels first extend along the carrier andthen transition into the cutting insert. The transition in this casetakes place in the axial direction and at interfaces of the coolantchannels arranged at the seat bottom of the seat.

SUMMARY

Against this background, it is an aim of the invention to specify amodular rotary tool with improved coolant supply. A correspondingcarrier and a corresponding cutting insert are also to be specified.

The task is achieved by a rotary tool having the features according toclaim 1, by a carrier having the features according to claim 14, and bya cutting insert having the features according to claim 15. Advantageousembodiments, refinements and variants are the subject matter of thedependent claims. The embodiments with respect to the rotary tool alsoapply analogously to the carrier and the cutting insert, and vice versa.

The rotary tool serves to in particular machine a workpiece and, forthis purpose, rotates during operation about an axis of rotationproceeding in a longitudinal direction. The rotary tool is in particulara drill. The rotary tool extends in the longitudinal direction andcomprises a carrier as well as a cutting insert, i.e., the rotary toolis designed to be modular. On the rear side, the carrier comprises ashaft, by means of which the carrier can be inserted, in particularclamped, into a machine tool. The cutting insert serves to machine theworkpiece and engages with it during operation. The cutting insert is,for example, a cutting plate or a cutting head. The cutting insertpreferably comprises a number of cutting edges, particularly preferablytwo cutting edges. The carrier and the cutting insert can in particularbe connected by means of a coupling. The carrier and the cutting insertare arranged one behind the other in the longitudinal direction.

The carrier comprises a seat, which comprises several lateral surfaces,between which the cutting insert can be inserted. The carrier moreovercomprises in particular a seat bottom, which is bordered and delimitedby the lateral surfaces. The seat bottom in particular proceedshorizontally, i.e., orthogonally to the longitudinal direction. Thelateral surfaces respectively proceed vertically, i.e., parallelly tothe longitudinal direction. The seat is formed as a recess in thecarrier and is generally approximately U-shaped. The carrier inparticular comprises a number of lateral arms, which surround thecutting insert in the inserted state and on which one of the lateralsurfaces is respectively arranged on the inside. The cutting insertcomprises, for each of the lateral surfaces, a contact surface whichabuts against the respective lateral surface in an inserted state. Indoing so, the contact surface and the lateral surface do not necessarilyhave to be congruent.

In the rotary tool, at least one coolant channel is formed, which servesto supply a coolant from a rear side of the rotary tool to a front side.Within the scope of the present application, the term “coolant” alsorefers to lubricant or coolant and lubricant. The coolant channelcomprises a first partial channel and a second partial channel, whichadjoins the first partial channel. The coolant channel in particularconsists of only one first and one second partial channel each. Thefirst partial channel proceeds within the carrier up to an outletopening. The outlet opening is formed on the carrier. The second partialchannel proceeds within the cutting insert and extends from an inletopening up to a preferably front-side coolant outlet. Via the coolantoutlet, the coolant is discharged from the rotary tool in the directionof the workpiece. The outlet opening in the carrier and the inletopening in the cutting insert form an interface for transferring coolantfrom the carrier to the cutting insert. To this end, the outlet openingand the inlet opening coincide in the assembled state. In the presentcase, the outlet opening is arranged in one of the lateral surfaces andthe inlet opening is arranged in one of the contact surfaces so that theinterface is formed laterally and not axially. “Laterally” is generallyunderstood to mean in particular “transversely to the longitudinaldirection” or more generally “in a direction that does not correspond tothe longitudinal direction”, i.e., generally in an inclined manner withrespect to the longitudinal direction, i.e., orthogonally oralternatively obliquely to the longitudinal direction.

The number of lateral arms, lateral surfaces, contact surfaces, andcoolant channels respectively preferably corresponds to the number ofcutting edges of the cutting insert. In the case of several coolantchannels, the coolant channels are preferably designed to be similar.

An essential aspect of the invention consists in particular in thecoolant supply from the carrier to the cutting head now taking placelaterally, i.e., in particular orthogonally to the longitudinaldirection. This is in particular in contrast to the method of DE 10 2014108 220 A1 mentioned at the beginning, in which the coolant supply takesplace axially, i.e., in the longitudinal direction and through the seatbottom. In such an axial coolant transfer, corresponding leakageresults. In the lateral, i.e., in particular radial, coolant transferaccording to the invention, the seat bottom is however correspondinglyunloaded and leakage of coolant is also advantageously avoided or atleast significantly reduced. At the same time, the transfer of coolantto the cutting insert and the positioning of the coolant outlets on thecutting insert ensure that the coolant is discharged as closely aspossible to the point where cooling is particularly required. This is incontrast to such designs in which the coolant outlets are arranged onthe carrier and the cutting insert itself does not comprise any coolantchannels. In these designs, cooling is only possible to a limitedextent. In contrast, particularly optimal cooling is ensured in thepresent case as a result of the arrangement of the coolant outlets inthe cutting insert.

In a suitable embodiment, the first partial channel first proceeds inthe longitudinal direction through the carrier to the front side and issubsequently bent on the front side and there proceeds transversely tothe longitudinal direction, i.e., as described above, at an incline tothe longitudinal direction, and in particular in or counter to adirection of rotation of the rotary tool or in a radial direction. Inother words: The first partial channel has a bent course and proceedsfrom a rear side of the carrier in the longitudinal direction, i.e.,axially, up to a front side of the carrier, in particular up to one ofthe lateral arms of the carrier, and then curves laterally there, inparticular at an angle of 90°, so that a lateral outlet opening results.The first partial channel thus follows an L-shaped course overall. Thefirst partial channel preferably proceeds helically from the rear sideand follows in particular a number of flutes, which are introduced intothe carrier.

The second partial channel expediently follows a curved or inclinedcourse, in particular with respect to the longitudinal direction, andfirst extends, starting from the inlet opening, in the radial directionand then curves in the longitudinal direction and toward the front side.In other words: The second partial channel proceeds at an incline or iscurved, e.g., L-shaped. The curved course makes it possible to have thesecond partial channel end at any point of the cutting head and thus toarbitrarily and therefore optimally position the coolant outlet.

However, a straight course between the inlet opening and the coolantoutlet is also suitable. In a suitable embodiment, the second partialchannel then follows a straight course. Such a straight course can bemanufactured particularly easily, particularly against the backgroundthat a particularly hard material is expediently used to produce thecutting insert.

In a particularly preferred embodiment, the lateral surfaces and thecontact surfaces are formed as torque transfer surfaces, which arepressed onto each other during operation of the rotary tool. A coolanttransfer in the torque transfer surfaces is particularly advantageoussince these torque transfer surfaces are in principle pressed againsteach other during operation and leakage of coolant is therebyparticularly effectively prevented. A torque transfer surface is inparticular characterized in that it interacts with another torquetransfer surface and that a torque transfer from the carrier to thecutting insert and vice versa thereby takes place.

The carrier and the cutting insert respectively comprise in particular anumber of clamping surfaces, which are pressed against each other in theassembled state in order to clamp the cutting insert in the carrier. Theclamping surfaces are thus in particular part of the coupling. Theaforementioned torque transfer surfaces are however in particular notclamping surfaces. Basically also suitable is a design in which thelateral surfaces are designed as clamping surfaces so that the coolanttransfer takes place through the clamping surfaces.

The clamping surfaces are however preferably free of outlet and inletopenings. This is based on the consideration that the clamping surfacesachieve a clamping effect, which holds the cutting insert in thecarrier, by means of friction and that this friction would be reduced byadditional outlet and inlet openings. By arranging the interface outsidethe clamping surfaces, i.e., by coolant transfer outside the clampingsurfaces, a particularly robust connection between the cutting insertand the carrier is thus ensured.

On the front side, the cutting insert comprises a number of end faces. Arespective end face is in particular a clearance surface which adjoins acutting edge of the cutting insert in a direction of rotation. Thus, anend face is formed for each cutting edge. In this respect, the directionof rotation is the direction in which the rotary tool rotates duringmaterial machining. In order to ensure optimal coolant supply to theworkpiece, the coolant outlet is formed inside the end face. The coolantoutlet is thus in particular necessarily arranged behind the cuttingedge in the direction of rotation. In particular, a coolant outlet isrespectively formed in each end face.

The end face is in particular delimited by a cutting edge as well as bya rear edge, which follows the cutting edge in the direction ofrotation. The end face is moreover delimited outwardly in the radialdirection by a circumferential edge and inwardly in the radial directionin particular by a cross-cutting edge or tool tip. In a preferredembodiment, the coolant outlet is then arranged on the rear edge. Inother words: The coolant outlet is located partially inside the end faceand partially in another clearance surface or partially in a flute thatadjoins the end face. Coolant discharge thus takes place both in theaxial direction from the end face as well as in the lateral directionthereto and counter to the direction of rotation.

Alternatively to the aforementioned positions of the coolant outlet,other positions are also suitable. In an advantageous variant, thecutting insert comprises a flute and the coolant channel opens out intothe flute. In other words: The coolant outlet is arranged in a flute ofthe cutting insert.

In a suitable development, the coolant channel opens out into aclearance surface of the flute or into a point thinning of the flute orinto both. The flute thus comprises a clearance surface or a pointthinning, which is arranged on the front side, or both a clearancesurface and a point thinning. The coolant channel then opens out intothe flute by the coolant channel opening out into either the clearancesurface or the point thinning or both. In the latter case, the clearancesurface and the point thinning in particular adjoin each other at aboundary line and the coolant channel opens at the boundary line. In asuitable embodiment, the boundary line corresponds in particular to theabove-described rear edge.

The described embodiments with the different positions of the coolantoutlet can also advantageously be combined with each other. In asuitable embodiment, the second partial channel is designed to bebranched, i.e., with several arms, and comprises several coolant outletsbut in particular still only one inlet opening. The different coolantoutlets of the single second partial channel are then advantageouslyarranged at different locations in order to ensure a particularlyneeds-based and effective coolant supply. In doing so, the coolantoutlets do not necessarily have to have identical cross-sections;rather, the cross-section of a respective coolant outlet and inparticular also of the associated arm is expediently selected dependingon the cooling capacity required at the respective location.

Particularly preferred is an embodiment, in which the carrier comprisesa number of flutes as well as a core, which is delimited by the flutes,and wherein the first partial channels in particular proceed completelyoutside the core. This external arrangement of the first partialchannels significantly improves the robustness of the carrier and thusof the entire rotary tool. In the case of a coolant transfer in the seatbottom, the first partial channels must necessarily proceedapproximately centrally in the carrier, i.e., in the core, whereby thecore is correspondingly weakened. As a result of the coolant transfertaking place laterally in the present case, it is however advantageouslypossible to position the first partial channels completely outside thecore and to keep the core free of coolant channels. The core is inparticular defined as the area of the carrier up to which the flutesextend. The core then has a radius that results as the differencebetween a total radius of the carrier and a depth of the flutes.

The carrier or the cutting insert or both are preferably produced bymeans of a 3D printing method. A 3D printing method has a particularlyhigh degree of freedom with respect to the design of the componentsproduced thereby so that the most varied geometries can be realized. Inthe present case, this is particularly advantageous with respect to thedesign of the coolant channels. The specific above-described courses ofthe coolant channels as a whole and specifically of the partial channelscan be realized particularly easily within the scope of a 3D printingmethod.

The carrier or the cutting insert or both are preferably respectivelymanufactured in one piece, i.e., produced from only one material. Whereapplicable, an additional coating is however applied. The carrier ispreferably manufactured from steel. The cutting insert is preferablymanufactured from hard metal.

As already mentioned, the aim is also respectively achieved by a carrieror a shaft as described above. Advantages and developments of thecarrier and of the cutting insert respectively as a single part resultaccordingly from the aforesaid.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is explained in detail below inreference to the drawing. Shown schematically in each case are:

FIG. 1 a carrier for a rotary tool,

FIG. 2 a section of the carrier in a side view,

FIG. 3 a cutting insert for a rotary tool.

DETAILED DESCRIPTION

FIGS. 1 and 2 show a carrier 2 for a rotary tool 4. FIG. 1 is aperspective view and FIG. 2 is a side view. FIG. 3 shows a perspectiveview of a cutting insert 6, which can be inserted into the carrier 2 ofFIGS. 1 and 2. The carrier 2 and the cutting insert 6 together form therotary tool 4, i.e., the rotary tool 4 is designed to be modular.

The rotary tool 4 serves to machine a workpiece not shown and, for thispurpose, rotates during operation about an axis of rotation A proceedingin a longitudinal direction L. The rotary tool 4 is in this case adrill. The carrier 2 and the cutting insert 6 respectively extend in thelongitudinal direction L. On its rear side, the carrier 2 comprises ashaft 8, by means of which the carrier 2 can be clamped into a machinetool not shown. The cutting insert 6 serves to machine the workpiece andengages with it during operation. The cutting insert 6 is in this casedesigned as a cutting head and comprises a number of cutting edges, inthis case two cutting edges 10.

The carrier 2 and the cutting insert 6 can in particular be connected bymeans of a coupling. In the mounted state, the carrier 2 and the cuttinginsert 6 are then arranged one behind the other in the longitudinaldirection L. In the present case, the coupling comprises a pin 12, whichis formed on the cutting insert 6, and a blind hole 14 in the carrier 2for receiving the pin 12. The carrier 2 moreover comprises several sidearms, in this case two side arms 16, for holding the cutting insert 6.In the assembled state, the side arms 16 rest on projections 18 on thecutting insert 6 so that the latter is encompassed as it were.Additionally formed both on the carrier 2 and on the cutting insert 6are several clamping surfaces 20, by means of which the cutting insert 6can be clamped in the carrier 2.

The carrier 2 moreover comprises as part of the coupling a seat 22,which comprises several lateral surfaces, in this case two lateralsurfaces 24, between which the cutting insert 6 can be inserted. Thecarrier 2, more precisely the seat 22, moreover comprises a seat bottom23, which is bordered and delimited by the lateral surfaces 24. In thiscase, the seat bottom 23 proceeds horizontally, i.e., orthogonally tothe longitudinal direction L, and the lateral surfaces 24 respectivelyproceed vertically, i.e., parallelly to the longitudinal direction L.The seat 22 as a whole is formed as a recess in the carrier 2 and isapproximately U-shaped as a result of the side arms 16. The cuttinginsert 6 comprises, for each of the lateral surfaces 24, a contactsurface 26 which abuts against the respective lateral surface 24 in aninserted state.

The rotary tool 4 comprises at least one coolant channel 28, in thepresent case even two coolant channels 28, which are designed to besimilar and which serve to supply a coolant from the rear side RS of therotary tool 4 to the front side FS. Each coolant channel 28 comprises afirst partial channel 30 and a second partial channel 32, which adjoinsthe first partial channel 30. The first partial channel 30 respectivelyproceeds completely within the carrier 2 up to an outlet opening 34. Thesecond partial channel 32 in contrast proceeds completely within thecutting insert 6 from an inlet opening 36 up to a front-side coolantoutlet 38, via which the coolant is discharged during operation from therotary tool 4 in the direction of the workpiece. The outlet opening 34in the carrier 2 and the inlet opening 36 in the cutting insert 6 forman interface 40 for transferring coolant from the carrier 2 to thecutting insert 6. This interface 40 is designed as a lateral or radialinterface 40 by arranging the outlet opening 34 in one of the lateralsurfaces 24 and the inlet opening 36 in one of the contact surfaces 26.

The first partial channel 30 first proceeds in the longitudinaldirection L through the carrier 2 up to one of the side arms 16 and issubsequently bent on the front side and proceeds orthogonally to thelongitudinal direction L. This can in particular be seen in FIGS. 1 and2, in which the bent course of the first partial channel 30 isillustrated by a line. The outlet opening 34 is then formed laterally onthe side arm 16. The first partial channel 30 thus follows an L-shapedcourse overall. In the exemplary embodiment shown, the first partialchannel 30 moreover proceeds helically from the rear side RS and, indoing so, follows a number of flutes 42, which are introduced into thecarrier 2.

The course of the second partial channel 32 is indicated by a line inFIG. 3. In this case, the course is straight, i.e., only inclined; incontrast, the second partial channel 32 follows a curved course in analternative not shown. In each case, the second partial channel 32however first extends, starting from the inlet opening 36, in the radialdirection R and then curves into the longitudinal direction L and towardthe front side FS.

In the exemplary embodiment of FIG. 1 through 3, the lateral surfaces 16and the contact surfaces 16 are respectively formed as torque transfersurfaces, which are pressed onto each other during operation of therotary tool 4. These torque transfer surfaces are different from theclamping surfaces 20. In an alternative not shown, the clamping surfaces20 however correspond to the lateral surfaces 16 so that the coolanttransfer then takes place through the clamping surfaces 20. As shown inthe figures, the clamping surfaces 20 are however preferably free ofoutlet and inlet openings 34, 36. The interface 40 is thus arrangedoutside the clamping surfaces 20.

On the front side, the cutting insert 6 comprises a number of end faces,in this case two end faces 44, which respectively adjoin one of thecutting edges 10 in a direction of rotation D. Each end face 44 isdelimited by a cutting edge 10 as well as by a rear edge 46, whichfollows the cutting edge 10 in the direction of rotation D. Each endface 44 is moreover delimited outwardly in the radial direction R by acircumferential edge 48 and inwardly in the radial direction R by across-cutting edge 50. An end face 44 is formed for each cutting edge10. The direction of rotation D is the direction in which the rotarytool 4 rotates about the axis of rotation A during material machining.The coolant outlets 38 are in the present case formed inside the endfaces 44, namely one coolant outlet 38 per end face 44. The coolantoutlets 38 are moreover arranged behind the cutting edges 10 in thedirection of rotation D. It can moreover be clearly seen in FIG. 3 thatthe coolant outlet 38 is arranged on the rear edge 46 and thus both inthe end face 44 and in one of the flutes 42, which adjoins the end face44 in the present exemplary embodiment. In an alternative not shown, thecoolant outlets 38 are positioned at another location on the cuttinginsert. In this respect, almost any design possibility results. In avariant not shown, the second partial channel 32 is designed to bebranched, with several arms, and comprises several coolant outlets 38.

As already mentioned, the carrier 2 comprises a number of flutes 42 inthe present case. Their course defines an internal core 52, which isdelimited by the flutes 42. As can be seen in FIGS. 1 and 2, the firstpartial channels 30 proceed completely outside the core 52, i.e., arearranged on the outside.

The invention claimed is:
 1. A rotary tool which extends in alongitudinal direction and which comprises a carrier as well as acutting insert, wherein the carrier comprises a seat, which comprisesseveral lateral surfaces, between which the cutting insert is configuredto be inserted, wherein the cutting insert comprises, for each of thelateral surfaces, a contact surface which abuts against the respectivelateral surface in an inserted state, wherein at least one coolantchannel is formed, which comprises a first partial channel and a secondpartial channel, which adjoins the first partial channel, wherein thefirst partial channel proceeds within the carrier and extends up to anoutlet opening, wherein the second partial channel proceeds within thecutting insert and extends from an inlet opening up to a coolant outlet,wherein the outlet opening and the inlet opening form an interface fortransferring coolant from the carrier to the cutting insert, wherein theoutlet opening is arranged in one of the lateral surfaces, wherein theinlet opening is arranged in one of the contact surfaces, and whereinthe lateral surfaces and the contact surfaces are designed as torquetransfer surfaces, which are pressed onto each other during operation.2. The rotary tool according to claim 1, wherein the first partialchannel first extends in the longitudinal direction through the carrierto a front side and subsequently is bent on the front side and proceedstransversely to the longitudinal direction.
 3. The rotary tool accordingto claim 1, wherein the second partial channel follows a curved courseand first proceeds, starting from the inlet opening, in a radialdirection and then curves in the longitudinal direction and toward afront side.
 4. The rotary tool according to claim 1, wherein the secondpartial channel follows a straight course.
 5. The rotary tool accordingto claim 1, wherein the carrier and the cutting insert respectivelycomprise a number of clamping surfaces, which are pressed against eachother in the assembled state in order to clamp the cutting insert in thecarrier and that the clamping surfaces are free of outlet and inletopenings.
 6. The rotary tool according to claim 1, wherein the cuttinginsert comprises on a front side an end face, inside which the coolantoutlet is formed.
 7. The rotary tool according to claim 6, wherein theend face is delimited by a cutting edge and by a rear edge, whichfollows the cutting edge in a direction of rotation, and the coolantoutlet is arranged on the rear edge.
 8. The rotary tool according toclaim 1, wherein the cutting insert comprises a flute and that thecoolant channel opens out into the flute.
 9. The rotary tool accordingto claim 1, wherein the coolant channel opens out into a clearancesurface of the flute or into a point thinning of the flute or into both.10. The rotary tool according to claim 1, wherein the second partialchannel is designed to be branched and comprises several coolantoutlets.
 11. The rotary tool according to claim 1, wherein the carriercomprises a number of flutes and a core, which is delimited by theflutes, and that the first partial channels proceed outside the core.12. The rotary tool according to claim 1, wherein the carrier or thecutting insert or both are produced via a 3D printing method.
 13. Therotary cutting tool according to claim 1, characterized in wherein therotary cutting tool is a drill.
 14. A carrier for a rotary toolaccording to claim
 1. 15. A cutting insert for a rotary tool accordingto claim
 1. 16. The rotary cutting tool according to claim 1, whereinthe torque transfer surfaces are not clamping surfaces.
 17. The rotarycutting tool according to claim 1, wherein the seat is formed as arecess in the carrier.
 18. The rotary cutting tool according to claim17, wherein: the seat includes: a seat bottom, and side arms, on whichthe lateral surfaces are disposed, the seat being approximately U-shapedas a result of the side arms and the seat bottom.
 19. The rotary cuttingtool according to claim 18, wherein the seat bottom is bordered anddelimited by the lateral surfaces.
 20. The rotary cutting tool accordingto claim 18, wherein: the seat bottom is oriented orthogonally withrespect to a longitudinal direction of the rotary cutting tool, and thelateral surfaces are oriented in parallel with respect to thelongitudinal direction of the rotary cutting tool.